EE 1402 POWER SYSTEM PROTECTION AND SWITCHGEAR Unit IV Question Bank

 

UNIT – IV

ALERNATOR AND TRANSMISSION LINE PROTECTION

PART – A (2 MARKS)

1. What are the types of stator winding faults in alternator?

2. Mention the most commonly used protection scheme for alternators.

3. What are the types of feeders in power system.

4. What is meant by radial feeder?

5. What is the disadvantage of radial feeder?

6. What are the relays used for time graded protection in radial feeders.

PART - B

1. Enumerate the relaying schemes which are employed for the protection of a modern alternator. (16)

2. (a) What is transverse or split phase protection of an alternator? (4)

(b) What type of fault is this scheme of protection employed? (4)

(c) With a neat sketch discuss the working principle of this scheme. (8)

3. What type of a protective device is used for the protection of an alternator against overheating of its (i) stator (ii) rotor? Discuss them in brief. (8+8)

4. What type of a protective scheme is employed for the protection of the field winding of the alternator against ground faults? (16)

5. Discuss the protection employed against loss of excitation of an alternator. (16)

6. (a) What do you understand by field suppression of an alternator? (8)

(b) How is it achieved? (8)

7. Briefly discuss the protection of an alternator against.

(i) Vibration of distortion of motor (4)

(ii) Bearing overheating (4)

(iii) Auxiliary failure (4)

(iv) Voltage regulator failure (4)

8. What type of pilot protection is used for EHV and UHV transmission lines. (16)

9. (a) What is carrier protection? (4)

(b) For what voltage range is it used for the protection of transmission line? (4)

(c) What are its merits and demerits? (8)

10. (a) What is carrier aided distance protection. (4)

(b) What are its different types? (4)

(c) Discuss the permissive under-reach transfer tripping scheme of protection. (8)

11. (a) Draw and explain the merz-price protection of alternator stator winding. (10)

(b) A generator is protected by restricted earth fault protection. The generator ratings are 13.2kv, 10MVA. The percentage of winding protected against phase to ground fault is 85%. The relay setting is such that it trips for 20% out of balance calculate the resistance to be added in the neutral to ground connection. (6)